Method of filtering solutions and apparatus therefor



Feb. 4, 1941. c MUNCH 2,230,307

METHOD OF FILTERING SOLUTI ONS AND APPARATUS THEREFOR File d June 22, 1938 5 Sheets-Sheet 1 I lgVA/TOR BY CHPL 'MU/VCH Cy (kw ATTORNEY Feb. 4, 1941. 'c. MUNCH 2,230,307

METHOD OF FILTERING SOLUTIONS AND APPARATUS THEREFOR Filed June 22, 1958 5 Sheets-Sheet 2 INL ENTOR CHRL 'MUNCH Q" ATTORNEY Feb. 4, 1941. 4 A c. MUNCH 2,233,307

METHOD OF FILTERING SOLUTIONS AND APPARATUS THEREFOR iled Jun 22, 1938 5 Sheets-Sheet 5 q a w 0 IN I ENTOR CARL MUNC'H Feb. 4, 1941. Q MUNCH 2,230,307

METHOD OF FILTERING SOLUTIONS AND APPARATUS THEREFOR Filed June 22, 1938 5 Sheets-Sheet' 4 VIIIIIIIIII/IIIII [)XVENTOR CARL MUNCH @W RNEY Feb. 4, 1941. c MUNCH 2,230,307

METHOD OF FILTERING SOLUTIONS AND APIARA I'US THEREFOR Filed June 22, 1938 5 Sheets-sheaf; 5

lNJ ENTOR BY CARL. MU/VCH ATTORNEY Patented Feb. 4, 1941 y 3 2,230,307

UNITED STATES PATENT. OFFICE METHOD OF FILTERING SOLUTIONS AND APPARATUS THEREFOR Carl Miinch, Leipzig, Germany Application June 22, 1938, Serial No. 215,143 In Germany June 26, 1937 12 Claims. (Cl. 210-62) The present invention relates to a method, of to provide a filtering process relying on the filterfiltering solutions, and, more particularly, to a ing effect in a gap formed between two rotary novel method of filtering solutions containing parbodies rotated at different speeds and having a ticles of pigments or other similar particles, and circumferential displacement in opposite direc- 5 to an apparatus therefor. tion in the gap.

Heretofore, the purification and filtering of Still another object of the invention is to prosolutions and the removal of the coarse-grained vide a filtering apparatus for carrying the procparticles of pigment and similar substances have ess of the invention into practice. generally been carried out by' means of screening The invention also contemplates a filtering ap- 1 the solutions. As those skilled in the art know, paratus involving a pair of rotary bodies having this conventional procedure was connected with smooth or corrugated surfaces cooperating with great disadvantages and difiiculties, particularly each other and. having a small space or gap due to the fact that the'orifices or holes of the therebetween for retaining the filtration residues. 1 screens were quickly cloggedand required fre- It is also within contemplation of the invention quent cleaning or replacement. When it was deto provide a novel and improved filtering appa- 15 sired to filterthin-fiowing solutions containing ratus which is simple in construction, easy and pigments, such as, for example, coating lacquers, inexpensive to operate, and which may be manuscreens up to 8000 meshes per square centimeter factured and sold-at a low price. frequently had to be used. A screen of this type Other and further objects and advantages of can reliably remove particles or grains as small the present invention will become apparent from 20 as about kmillimeter in diameter. However, the following description taken in conjunction screens of this character and dimensions were with the accompanying drawings, in whichrather expensive and had but very little struc- Fig. 1 illustrates a vertical sectional view, sometural strength. Also these screens would frewhat diagrammatic in character, of a filtering quently break or tear without the failures being apparatus embodying the principles of the presnoticed, whereby the filtering efliciency became ent invention;

highly problematical. These fine screens could Fig. 2 depicts a similar view of a modified emnot be employed for the filtration of thick-fiowbodiment of the present invention;

ing masses, such as artificial leather masses. Fig. 3 depicts a side elevational detail view,

Therefore, in the filtration of viscous liquids or somewhat fragmentary, of the laminated filter- 3 thick-flowing masses, it was necessary to employ ing roll shown in Fig. 2; d much coarser screens, whereby the degree of fil- F 4 is Side elevational View Of a Pa Of tration was greatly reduced. Although this 111- filtration rolls having serrated circumferential tration problem existedfor a considerable length surfaces;

of time and various suggestions and proposals Fig. 5 is a top elevational view, also fragmen- 35 were made for the solution thereof, none, as far tary, of the rolls shown in Fig. 4; as is known, of these various suggestions and Fig. 6 illustrates aside elevational view of a proposals was completely satisfactory and sucpair of filtration rolls embodying the invention cessful on a practical and industrial scale. and having a laminated character;

It has been discovered that the outstanding sdepicts a p v l i w. m wha in problem may be solved in a simple, positive and fragmentary, of the rolls shown in-Fig. 6; satisfactory manner. 'Fig. 8 shows a side elevational view of a lami- It is an object of the present invention to pronated filtration roll of a'modified' character; vide a filtration process, particularly for the fil- Fig. 9 is a top elevational view, somewhat tration of thick, masses containing sman solid fragmentary. of the roll shown in Fig. 8 and of 5- particles, which is free from the disadvantages the comb-like scraper member cooperating thereand inconveniences of conventional filtering procwith; 1 esses. i Fig. 10 illustrates a vertical sectional view,

It is another object of the invention to provide somewhat diagrammatic in character, of a filtera filtering process which dispenses with the 10- ing apparatus embodying a roll of laminated 0 rami'nous members, screens, sieves, and the like, character;

of the conventional filtering processes and which Fig. 11 depicts a similar view of a filtering employs a narrow gap or a plurality of such gaps apparatus embodying the invention and having a instead, pair of laminated rolls cooperating with each l't-is a further object of the present invention other incorporated therein 55 liquid. Rolls 3 and 4 parts in elevation, of a further modified embodiment of the invention involving-a series of cooperating filtering rolls of laminated character;

and

Fig. 13 is a similar view of a modified embodiment of the invention having a series of smoothfaced filtering rolls incorporated therein.

Broadly stated, according to the principles of the present invention, screens, sieves, filtering cloths and other foraminous members are dispensed with, and the purification and filtration of the solutions to be treated are accomplished by passing the solutions through a narrow gap which is capable of retaining the impurities. The narrow gap is preferably formed by'means of two bodies, each of which is defined by a surface of revolution, such as, for example, two rolls having smooth cylindrical surfaces arranged in parallel spaced relationship to form a narrow gap therebetween. Instead of smooth rolls, it is also possible to employ cooperating rolls having serrated or grooved surfaces, whereby the gap or gaps may have an accentuated length, and an increased filtering efiiciency may be obtained. Likewise, it;

plurality of plates arranged on a shaft in parallel spaced relationship and at such distances from each other that between the individual plates filtration gaps of predetermined dimensions are formed. These laminated rolls may be employed in combination'with comb-like scrapers or may be arranged in cooperating positions with each other. The rolls or other rotation bodies are rotated at different velocities and in such sense that the circumferential displacement of cooperating rolls is in the opposite direction in the gap. A plurality of such filters or cooperating filtering rolls may be arranged in series-.orsin cascade to obtain increased filtering efiicien'cy and output, as those skilled in the art will readily understand.

Referring now more particularly to Fig. 1 of the drawings, a preferred embodiment of the invention is illustrated. The filtering apparatus essentially comprises an upper tank orhopper I holding a body of liquid 2 to be filtered therein. The lower end of tank I is closed by means of a pair of-filtration rolls 3 and 4 rotatably mounted in parallel spaced relationship and having a narrow gap 5 therebetween through which filtered liquid may flow during the operation of the device. Underneath rolls 3 and 4 is provided a second tank 6 for receiving the filtered and purified are rotated at different velocities, roll 4 being rotated much faster than roll 3. In addition, the rolls are rotated in the same sense so that the cylindrical surfaces of the rolls move in opposite direction in the gap, as is indicated by arrows 1 and 8. Due to the described rotation of the rolls, all impurities which are coarser than the gap or the distance between the surface of the rolls will be carried back by means of the faster roll 4 into the hopper and are scraped off from the roll by means of scraper 9. The purified and filtered solution will pass through the gap between the, rolls and is scraped oif from the circumferential surface of roll 3 by means of a scraper Ill. In hopper I above the rolls, two guide plates I I and I2 are preferably provided. Of these, the first guide plate I I operates-muchin the same manner as a doctor blade and has the object of-distributing the liquid on the surface of roll 3.

especially in the case of thick flowing solutions. The second guide plate I2 has the object of preretained in the intervals between This is very .essential,

venting admixture of the solution returned by roll 4 into upper tank or hopper I with the untreated solution in said tank.

In the narrow channel I3 underneath guide plate I2, the separated solution is driven upwards by the rotation of roll 4 and is returned into the upper tank or hopper -I. The impurities would gradually accumulate in the upper tank were channel I3 not separated from the upper tank proper by means of a screen or foraminous partition wall I4. The only disadvantage of this arrangement resides in the frequent clogging of screen I4 by means of the thick-flowing liquid. Moreover, in view of the thick-flowing character of the liquid to be treated, this screen must have a very coarse mesh which greatly limits the degree of filtering. Therefore, it has been found that better operating results .are obtained by means of the arrangement illustrated in Fig. 2.

As it will appear from the drawing, the filtering apparatus depicted in Fig. 2 shows all of the essential partsof Fig. 1, such as an upper tank 2I, holding a body of liquid 22, a lower tank 26, a pair of cooperating filtering rolls 23 and 24 having a small gap 25 therebetween and rotated in the directions indicated by arrows 21 Likewise, rolls. 23 and 24' are provided with scrapers 30 and 29, respectively, and with guide plates 3| and 32 which have the same arrangement and the same function as in Fig. 1.' The novel element of this combination is roll 35 constituted of thin and round plates 36 which are spacedly mounted on a shaft 31 at a distance from each other corresponding to the desired degree of filtration. The solution returned into channel 33 is forced into the intervals of plates\,36. Coarse grainedimpurities will get caught in. the circumferential portions of removed by scraper member 38 lected in compartment 39. The

and will be .col-' filtered solution the individual plates is removed by means of a comb-like scraper 40. In this manner it is possible continuously to filter any desired quantities of a unitary solution without any interruptions. All that is necessary is to remove theaccumulated impurities from time to time from cbmpartment or cell 39.

Instead of cylindrical rolls having smooth circumferential surfaces, it is also possible to employ rolls having various grooved surface formations provided in such manner that the corresponding portions of the grooves of one roll c'onform to similar portions of the .other cooperating roll. Thus, Figs. 4 and 5 illustrate cooperating rolls 4| and 42 having serrated surfaces which are rotated in the directions of arrows 43 and 44 respectively. A small gap 45 is provided between the two rolls'for the passage of the filtered liquid. Scrapers 46 and 41 having profiles corresponding to the faces of rolls 4| and. 42 cooperate with the filtration rolls, as described above.

A similar modification is depicted in Figs. 6 and 7. In this modification, a plurality of plates GI separated from each other by means of members -62 are provided on a shaft 63, and form afiltration member 64. A similar combination of a shaft 65, plates 66 and members 61 provides a second filtration member 68, adapted to cooperate with the first one and to provide a long, zig-zag shaped filtration gap 69, similar to gap 45 of Figs. 4 and 5. The two filtration members are rotated in the direction of the arrows I0 and II, and their operation will be readily understood by those skilled in the art without any further T and .28.

III

the plates, will be explanation. The advantage of the filtration members shown in Figs. 4 and 5, and in Figs. 6 and 7 resides in the accentuated length of the filtration gap, whereby a greater output of filtered liquid may be obtained in the same unit of time.

The filtering members shown in Figs. 8 and 9 are a. further'development of the basic inventive concept. In this case a rotatable body or filtration member BI is provided which is integrally formed of a single piece of metal having deep grooves provided therein for example by means of turning. These. grooves are fine enough to provide a filtering effect of their own and to retain particles which are coarser than the dimensions of the grooves. Filtration members of this type may also be provided by mounting a plurality of thin, circular plates 82 on a shaft 83 in parallel spaced relationship. The correct and accurate spacing of these plates is best ascer-- tained by means of suitable separating disks or washers 84 interposed between successive plates. Scrapers 85 and 86 of suitable form cooperate with filtration member 8! rotated in the direction of arrow 8'I. Regardless of their method of manufacture, filtration rolls or members of this type will be referred to in the following as laminated rolls or laminated filtration members.

The application of laminated filtration members provides a number of novel and highly effective combinations which are considerably different from the filtering apparatus described above.

The simplest form of a filtering apparatus embodying a laminated filtration member is illustrated in Fig. 10. An upper container IOI is provided for holding the liquid I02 to be filtered, its bottom portion being closed by means of a laminated filtration roll I03, so that the liquid has to pass to the interspaces between the individual plates of the roll. By means of the rotation of laminated roll I03 in the direction of arrow I04, and due to the gradual narrowing of flow channel I05, the solution is forced into the interspaces between the individual plates. All impurities which are larger in size than these intervals between the plates are deposited on the circumference of the laminated roll and would quickly clog all of the interspaces were it not for the scraper I06 which continuously removes these deposits. Scraper I06 is provided with short,

hooked teeth which extend a few millimeters into the interspaces in order to remove also the impurities deposited therein. In this manner, all of the impurities are accumulated in a compartment or cell II" from which they may be removed from time to time. The other side of laminated roll I03 is completely closed by means of a laminated or comb-like scraper I08 which extends into the interspaces of the individual plates up to the shaft whereby the filtered liquid filling out said interspaces may be completely re- -moved. The removed, filtered solution flows into a tank I09 provided in the lower portion of the filtering apparatus. During the rotation of laminated roll I03 a partial vacuum would be produced above the roll which has to be filled out by the continuous streaming of fresh liquid into the interspaces of the laminated roll. In other words, a powerful suction eflect is exerted-on the liquid above the filtration roll and further promotes the filtration process. Instead of providing a compartment orcell I01 for the storage of the separated impurities and of a slight portion of the solution removed together wiih the impurities, it is also possible to pass this rel. loved filtering apparatus of Fig.

is highly uncertain, and the wear on the brush rolls is very great in practical operation. More-= over, it cannot 'be completely avoided that parts of the wire forming the brush rolls break oil" and contaminate the filtered and treated solution.

Fig. 11 illustrates a modified arrangement in a laminated roll filter embodying a pair of laminated rolls. This filteringapparatus comprises an upper container or tank iii, which is closed at the bottom thereof by a pair of laminated filtration rolls H2 and H3, arranged in such cooperating position that the plates of each filtration roll extend into the interspaces of the other and displace the filtered solution from said interspaces. Laminated filtration rolls II? and M3 are rotated in the direction of arrows 8 Id and I it, the impurities retained close to the circumference thereof being removed by means of laterally arranged scrapers H8 and Ill and are deposited in compartments H8 and H9. In the central portion of the liquid body above the two lami-,

going and illustrated in Fig. 10. The filtered solution is discharged into a lower container or tank I20, located underneath rolls M2 and IE3.

Fig. 12 illustrates a further modified embodiment of the invention in which a series of laminated filtration rolls are provided in series or cascade operation. The filtering apparatus comprises a casing I2I having a container $22 for the liquid to be filtered and a container I23 for the filtered liquid and is supported by means of a cast iron or similar frame I2d. A plurality of laminated filtration rolls I25 are rotatably mounted in parallel spaced relationship within casing IZQ in such a manner that the plates are extending into the interspaces of the adjoining filtration rolls to a limited extent, preferably only to the extent of a few millimeters. All of the rolls are rotated in the same sense, as indicated by arrows I26. During the operation of the device, the liquid to be filtered is introduced into the interspaces of the first filtration roll from the conbe filtered to the first filtration roll, it may be easily accomplished that the impurities practically free from liquid may be stripped ofi from w the last roll by means of a scraper I21 and may be deposited in a compartment I28. Scrapers or stripper blades I29 of suitable form'are provided for each-of the rolls for displacing the filtered liquid from the interspaces of the plates of the laminated rolls; A positive suction effect is exerted on the space above the rolls by means of the operation of stripper or scraper members I29.

Fig. 13 illustrates an embodiment in which a series of smooth filtration rolls is employed. The

13 is very similar to the one shown in Fig. 12 and comprises a casing -so adjusted that the solution is only sufficient for filling out the first intervals between the rolls, whereas the last is filled only to a very limited extent. Therefore, coarse grained impurities will be'gradually transferred to and will accumulate on the last roll wherefrom they may be stripped by means of a scraper member I 38 and may be withdrawn into a compartment I39. The filtered solution is removed from the individual rolls by means of scrapers I 40 and accumulatesin lower container I33. Guide plates MI may be provided above the surface of each roll in order to cause better distribution of the liquid on the surface of the roll.

The output of a filter of the described character is quite considerable. Assuming that there are 6 rolls employed, each having 1 square meter of circlmlferential surface, and arranged to pro vide gaps of 0.1 millimeter, this arrangement is capable of delivering 1 cubic meter of filtered solution in 50 minutes at 50 revolutions of the rolls per minute, regardless of whether thickflowing or thin-flowing liquids are to be filtered. The distance of 0.1 millimeter between the adjoining rolls corresponds to a screen having-5000 meshes per square centimeter. The filtration of thick flowing liquids to such a considerable extent was heretofore completely impossible.

Although the present invention has been described in connection with a few preferred embodiments thereof, variations and modifications may be resorted to by those skilled in the art without departing from the principles of the present invention. Thus, laminated rolls may be employed in cooperating combinations with smooth rolls. The rolls may be arranged in various different relative positions, the flow of the liquid to be filtered may be directed downwards or upwards, according to the particular case contemplated. Guide plates, scrapers and strippers of many different types may .be employed. All of these variations and modifications, however, embody the same principle of the invention; to wit: the continuous filtration through gaps which are formed between or in rotation bodies and involving continuous removal of the impurities by rotating said body and by means of stripper and scraper members.

The process and the apparatus of the invention may be employed for fiitrations of all descrip- V .tions. The novel filtration process is of especial importance and value for the filtration of thickfiowing liquids which heretofore could not be filtered in a satisfactory manner on an industrial scale, such as artificial leather masses and the like, and masses produced in kneading machines for various purposes. 4

I claim:

1. The process of filtering solutions which comprises establishing at least one filtration gap between the circumferential surfaces of at least one pair of rotation bodies, passing a liquid to be Iiitered through said gap, causing rotation of said surfaces in the same sense and in opposite direction in the gap, removing filtered liquid from one of said surfaces, .from the other of said surfaces.

2. The process of filtering solutions which comprises establishing a filtration gap between a pair of rotary surfaces, passing a liquid to be filtered through said gap, causing rotation of said surfaces in the same sense and in opposite direction in the gap, removing filtered liquid from the surface moving in the direction of flow of the liquid in said gap, from the other of said surfaces moving in the opposite direction in said gap.

3. The process of filtering solutions which comprises establishing a filtration gap between a pair and removing filtration residues and removing filtration residues of rotary surfaces, passing a liquid to be filtered through said gap, causing rotation of said surfaces in the same sense and in opposite direction in the gap, the surface rotated against the flow of liquid in the gap having a considerably greater velocity, removing filtered liquid from the slower moving surface, and removing filtration residues from the faster moving surface.

4. The process of filtering solutions which comprises establishing a filtration gap adapted to retain impurities of predetermined size between a pair of smooth rotary surfaces, passing a, liquid to be filtered through said gap, said'surfaces in the same sense and in opposite direction in the gap, the surface moving in the direction of fiow of the liquid in said gap, and removing filtration residue from the other of said surfaces moving in the opposite direction in said gap.

5. The process of filtering thick-flowing masses which comprises establishing a filtration gap between a pair of rotary bodies, said gap having dimensions corresponding to the-desired degree of filtration, passing a thick-flowing mass to be filtered through said gap, rotating said rotary bodies at predetermined relative velocities having at least one of said bodies rotating in a direction opposite to that of the mass in the ap, removing filtration residues from said rotary body at a point above said gap, and removing filtered mass from the surface of the second rotary body whereby said filtration gap is formed by the cleaned surfaces of said bodies and remains permanently open and free fron impurities.

removing filtered liquid from causing rotation of 7. In an apparatus for filtering liquids, the' combination comprising a pair of cylindrical filtration bodies rotatably mounted in parallel spaced relationship to form a filtration gap, means for feeding liquid to be filtered to said gap,

means for rotating said bodies in the same sense V gap, means for filtration body and in opposite direction in said removing filtered liquid from the moving in the direction of the flow of liquid in said gap, and means for removing filtration residues from the other of saidsurfaces moving in the opposite direction in said gap.

8. In an apparatus for filtering liquids, the combination comprising a pair of cylindrical filtration rolls rotatably mounted in parallel spaced relationship to form a filtration gap, means for feeding liquid to be filtered to said gap, means for rotating said rolls in the same sense and in opposite direction in said gap, the roll rotated against the flow of liquid in the gap having a considerably greater velocity, means for removing filtered liquid from the surface of the slower filtration roll, and means for, removing filtration residues from the surface of the faster filtration roll.

9. In an apparatus for filtering liquids, the combination comprising a pair of cylindrical filtration rolls rotatably mounted in parallel spaced relationship to form a filtration gap, means for feeding liquid to be filtered to said gap, means for rotating said rolls in the same sense and in opposite direction in said gap, the roll rotated against the flow of liquid in the gap having a considerably greater velocity, means for removing filtered liquid from the surface of the slower filtration roll, means for removing filtration residues from the surface of the faster filtration roll, and guide plates cooperating with said filtration rolls above said gap to distribute said liquid on the surface of said slower roll and to prevent contamination of the liquid to be filtered with the filtration residues returned by said faster roll.

10. In an apparatus for filtering liquids, the combination comprising a pair of filtration rolls having serrated circumferential surfaces rotatably mounted in parallel spaced relationship and adapted to cooperate with each other to form a filtration gap of accentuated length, means for feeding liquid to be filtered to said gap, means for rotating said rolls in the same sense and in op- 'posite direction in said gap, the roll rotated against the flow of liquid in the gap having a considerably greater velocity than the other, means for removing filtered liquid from the surface of the slower filtration roll, and means for removing filtration residues from the surface of the faster filtration roll.

11. In an apparatus for filtering liquids, the combination comprising a pair of filtration rolls having grooved circumferential surfaces of an interlocking character rotatably mounted in parallel spaced relationship and adapted to cooperate with each other to form a filtration gap of accentuated length, means for feeding liquid to be filtered to said gap, means for rotating said rolls in the same sense and in opposite direction insaid gap, the roll rotated against the flow of liquid in the gap having a considerably greater velocity than the other, means for removing filtered liquid from the surface of the slower filtration roll, and means for removing filtration residues from the surface of the faster filtration roll;

'12. In an apparatus for filtering liquids, the combination comprising a plurality of filtration rolls rotatably mounted in parallel spaced relationship to form a filtration gap between sach pair of adjoining rolls, means for feeding liquid to be filtered to the first one of said gaps, means for rotating all of said rolls in the same sense and in opposite direction in the respective gaps to cause transfer of filtration residues from each roll to the next one along the series, means for permanently removing said residues from the last roll of the series, and means for removing filtered liquid from the underface of each of said rolls.

CARL METNCH. 

